Clays and Clay Minerals

, Volume 43, Issue 2, pp 196–211 | Cite as

Dehydroxylation of Aluminous Goethite: Unit Cell Dimensions, Crystal Size and Surface Area

  • H. D. Ruan
  • R. J. Gilkes


This work investigates unit cell dimensions, crystal size and specific surface area of aluminous goethite that was progressively dehydroxylated to form hematite. Goethite synthesized from the ferrous system altered to hematite with DTGA maximum increasing from 236° to 273°C for 0 to 30.1 mole % Al-substitution. Unit cell dimensions of goethite and hematite decreased as Al-substitution increased and increased as excess OH increased. The crystallographically equivalent a axis of goethite and c axis of hematite were more sensitive than other axes to the presence of excess structural OH associated with Al-substitution. Specific surface area increased from 147 to 288 m2/g for goethite and from 171 to 230 m2/g for hematite as Al-substitution increased. An increase in specific surface area on heating goethite at temperatures between 200° and 240°C is related to a decrease in the size of coherently diffracting domains of goethite crystals and to the development of pore and structural defects associated with the formation of hematite. The decrease in specific surface area for heating temperatures above 240°C is attributed to the growth of hematite crystals by diffusion.

Key Words

Al-substitution Crystal size Dehydroxylation Goethite Hematite Specific surface area Unit cell 


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Anand, R. R., and R. J. Gilkes. 1984. Weathering of hornblende, plagioclase and chlorite in Meta-Dolerite Australia. Geoderma 34: 261–280.CrossRefGoogle Scholar
  2. Bemal, J. D., D. R. Dasgupta, and A. L. Mackay. 1959. The oxides and hydroxides of iron and their structural interrelationships. Clay Miner. Bulletin 4: 15–30.CrossRefGoogle Scholar
  3. Brown, G. 1980. Crystal Structure of Clay Minerals and their X-ray Identification. G. W. Brindley and G. Brown, eds. London: Mineralogical Society, pp. 361–410.Google Scholar
  4. DeGrave, E., L. H. Bowen, and S. B. Weed. 1982. Mössbauer study of aluminum substituted hematites. J. Magn. & Magn. Mat. 72: 129–140.CrossRefGoogle Scholar
  5. Fazey, P. G., B. H. O’Connor, and L. C. Hammond. 1991. X-Ray powder diffraction rietveld characterization of synthetic aluminum-substituted goethite. Clays & Clay Miner. 39: 248–253.CrossRefGoogle Scholar
  6. Fey, M. B., and J. B. Dixon. 1981. Synthesis and properties of poorly crystalline hydrated aluminous goethites. Clays & Clay Miner. 29: 91–100.CrossRefGoogle Scholar
  7. Francombe, M. H., and H. P. Rooksby. 1959. Structure transformations effected by the dehydration of diaspore, goethite and delta ferric oxide. Clay Miner. Bulletin 21: 1–14.CrossRefGoogle Scholar
  8. Goodman, B. A., and D. G. Lewis. 1981. Mössbauer spectra of aluminous goethite (α-FeOOH). J. Soil Sci. 32: 351–363.CrossRefGoogle Scholar
  9. Goss, C. J. 1987. The kinetics and reaction mechanism of the goethite to hematite transformation. Miner. Mag. 51: 437–451.CrossRefGoogle Scholar
  10. Gregg, S. J., and K. J. Hill. 1953. The production of active solids by thermal decomposition. Part II. Ferric oxide. J. Chem. Soc. IV: 3945–3951.CrossRefGoogle Scholar
  11. Jónás, K., and K. Solymár. 1970. Preparation, X-ray, derivatographic and infrared study of aluminium-substituted goethites. Acta Chim. Acad. Sci. Hung. 66: 383–394.Google Scholar
  12. Lewis, D. G., and U. Schwertmann. 1979. The influence of Al on iron oxides. III. Preparation of Al-goethite in M KOH. Clay Miner. 14: 115–126.CrossRefGoogle Scholar
  13. Lewis, D. G., and U. Schwertmann. 1980. The effect of [OH] on the goethite produced from ferrihydrite under alkaline conditions. J. Colloid Interface Sci. 78: 543–553.CrossRefGoogle Scholar
  14. Lim-Nunez, R. S. L. 1985. Synthesis and acid dissolution of metal-substituted goethites and hematites: MSc. thesis. Department of Soil and Plant Nutrition, U.W.A., Nedlands, 6009, pp. 104–121.Google Scholar
  15. Mackenzie, R. C., and G. Berggren. 1970. Oxides and hydroxides of higher valence elements. In Differential Thermal Analysis 1. R. C. Mackenzie, ed. New York: Academic Press, 271–302.Google Scholar
  16. McKeague, J. A., and J. H. Day. 1966. Dithionite- and oxalate-extractable Fe and Al as aids in differentiating various classes of soils. Can. J. Soil Sci. 46: 13–22.CrossRefGoogle Scholar
  17. Naono, H., and R. Fujiwara. 1980. Micropore formation due to thermal decomposition of acicular microcrystals of α-FeOOH. J. Colloid Interface Sci. 73: 406–415.CrossRefGoogle Scholar
  18. Novak, G. A., and A. A. Colville. 1989. A practical interactive least-squares cell-parameter program using an electronic spreadsheet and a personal computer. Amer. Miner. 74: 488–490.Google Scholar
  19. Okamoto, G., R. Furuichi, and N. Sato. 1967. Chemical reactivity and electrical conductivity of hydrous ferric oxide. Electrochim. Acta 12: 1287–1299.CrossRefGoogle Scholar
  20. Permet, G., and R. Lafont. 1972a. Sur le paramétres cristallographiques des hématites aluminineuses. C. R. Acad. Sci. 275: 1021–1024.Google Scholar
  21. Perinet, G., and R. Lafont. 1972b. Sur la présence d’hématite aluminineuses désordonée dans des bauxites du Var. C. R. Acad. Sci. 274: 272–274.Google Scholar
  22. Rendon, J. L., J. Cornejo, P. Dearambarri, and C. J. Serna. 1983. Pore structure of thermally treated goethite (α-FeOOH). J. Colloid Interface Sci. 92: 508–516.CrossRefGoogle Scholar
  23. Schulze, D. G. 1982. The identification of iron oxides by differential X-ray diffraction and the influence of aluminum substitution on the structure of goethite: Ph.D. thesis. Lehrstuhl für Bodenkunde der Technischen Universität München, Weihenstephan.Google Scholar
  24. Schulze, D. G. 1984. The influence of aluminum on iron oxides. VIII. Unit-cell dimensions of Al-substituted goethites and estimation of Al from them. Clay & Clay Miner. 32: 36–44.CrossRefGoogle Scholar
  25. Schulze, D. G., and U. Schwertmann. 1984. The influence of aluminium on iron oxides: X. Properties of Al-substituted goethites. Clay Miner. 19: 521–539.CrossRefGoogle Scholar
  26. Schulze, D. G., and U. Schwertmann. 1987. The influence of aluminium on iron oxides: XIII. Properties of goethites synthesised in 0.3 M KOH at 25°C. Clay Miner. 22: 83–92.CrossRefGoogle Scholar
  27. Schwertmann, U., P. Cambier, and E. Murad. 1985. Properties of goethites of varying crystallinity. Clays & Clay Miner. 33: 369–378.CrossRefGoogle Scholar
  28. Schwertmann, U., R. W. Fitzpatrick, R. M. Taylor, and D. G. Lewis. 1979. The influence of aluminium on iron oxides. Part II. Preparation and properties of Al-substituted hematites. Clays & Clay Miner. 27: 105–112.CrossRefGoogle Scholar
  29. Singh, B., and R. J. Gilkes. 1992. XPAS: An interactive computer program for analysis of X-ray powder diffraction patterns. Powder Diffraction 7: 6–10.CrossRefGoogle Scholar
  30. Stanjek, H., and U. Schwertmann. 1992. The influence of aluminium on iron oxides. Part XVI: Hydroxyl and aluminium substitution in synthetic hematites. Clays & Clay Miner. 40: 347–354.CrossRefGoogle Scholar
  31. Taylor, M. R., and U. Schwertmann. 1978. The influence of aluminium on iron oxides. Part I. The influence of Al on Fe oxide formation from the Fe (II) system. Clays & Clay Miner. 26: 373–383.CrossRefGoogle Scholar
  32. Thiel, R. 1963. Zum system α-FeOOH-α-AlOOH. Z. Anorg. Allg. Chem. 326: 70–78.CrossRefGoogle Scholar
  33. Watari, F., J. van Landuyt, P. Delavignette, and S. Amelinckx. 1979. Electron microscopic study of dehydration transformations I. Twin formation and mosaic structure in hematite derived from goethite. J. Solid State Chem. 29:137–150.CrossRefGoogle Scholar
  34. Watari, F., P. Delavignette, J. van Landuyt, and S. Amelinckx. 1983. Electron microscopic study of dehydration transformations III. High resolution observation of the reaction process FeOOH → Fe2O3. J. Solid State Chem. 48: 49–64.CrossRefGoogle Scholar
  35. Wells, M. A., R. J. Gilkes, and R. R. Anand. 1989. The formation of corundum and aluminous hematite by the thermal dehydroxylation of aluminous goethite. Clay Miner. 24: 513–530.CrossRefGoogle Scholar
  36. Wolska, E., 1981. The structure of hydrohematite. Z. Kristallographie 154: 69–75.Google Scholar
  37. Wolska, E., and U. Schwertmann. 1989. Nonstoichiometric structures during dehydroxylation of goethite. Z. Kristallographie 189: 223–237.Google Scholar
  38. Wolska, E., and W. Szajda. 1985. Structural and spectroscopic characteristics of synthetic hydrohematite. J. Mater. Sci. 20:4407–4412.CrossRefGoogle Scholar

Copyright information

© The Clay Minerals Society 1995

Authors and Affiliations

  • H. D. Ruan
    • 1
  • R. J. Gilkes
    • 1
  1. 1.Soil Science and Plant Nutrition, Faculty of AgricultureUniversity of Western AustraliaNedlandsAustralia

Personalised recommendations